Numerous bone conditions or spinal injury can cause painful collapse of vertebral bodies, including osteopenia (osteoporosis), vertebral hemangiomas, multiple myeloma, necorotic lesions (Kummel's Disease, Avascular Necrosis), metastatic disease and complications from steroid and non-steroidal anti-inflammatory drug (NSAID) use. Osteoporosis is a systemic, progressive and chronic disease that is usually characterized by low bone mineral density, deterioration of bony architecture, and reduced overall bone strength. Vertebral body compression fractures (VCF) are more common in people who suffer from these medical indications, often resulting in pain, compromises to activities of daily living, and even prolonged disability. Likewise, degenerative and injured spinal disk rehabilitation (pharmacological or gene therapeutic) protocols to delay the progression of intradiscal diseases, or even to restore disk health and disk functions, are a part of contemporary research developments and emerging standards of care.
The science of spinal intervention has made great strides in recent years. On some occasions, spinal or poly-trauma patients experience VCFs that may be repaired by vertebroplasty and other spinal reconstructive means. Vertebroplasty, which literally means fixing the vertebral body, has been used in the United States since the mid-1990s to treat pain and progressive deterioration associated with VCF. Most often in this vertebroplasty procedure, a bone cement, like opacified polymethylmethacrylate (PMMA), or other suitable biomaterial alternatives or combinations, is injected percutaneously into the bony architecture under radiographic guidance and controls. The hardening (polymerization) of the cement media or the mechanical interlocking of other biomaterials serve to buttress the bony vault of the vertebral body, providing both increased structural integrity and decreased potential for painful micromotion and progressive collapse of the vertebrae and spinal column.
Bone tamps (bone balloons or Kyphoplasty™), a contemporary balloon-assisted vertebroplasty alternative for treatment of VCF, also involves injection of a bone cement into a mechanically created bone void within vertebral body. In this alternative vertebroplasty procedure, a balloon tamp is first inserted into the structurally compromised vertebral body, often through a cannula. The bone balloon is then deployed under high pressure. The expanding balloon disrupts the cancellous bone architecture and physiological matrix circumferentially and directs the attendant bony debris and physiologic matrix toward the inner cortex of the vertebral body vault. The balloon tamp is then collapsed and removed, leaving a bony void or cavity. The remaining void or cavity is repaired by filling it with an appropriate biomaterial media, most often bone cement. In most cases, the treatment goals are to reduce or eliminate pain and the risk of progressive fracture of the vertebral body and its likely resulting morbidity, complications, and disability.
Although most of these interventional procedures are an improvement over previous conservative treatments that consisted of bed rest, pharmaceuticals, and/or cumbersome back braces, these methods still suffer from the complication of potential leakage of the therapeutic biomaterial repair media (bone cement, etc.) outside of the desired treatment zone. Numerous risks are associated with these spinal interventional procedures. The risks and complications, which are related to the leakage of the biomaterial into structures that are intended to be preserved, may involve extravasation of the biomaterial into veins and/or lungs, infections, bleeding, rib or pedicle fracture, pneumothorax, increased pain, a range of soft and/or neural tissue impingement, paresis, and paralysis. Most clinicians prefer to focus or contain treatments to the injured or diseased tissues alone.
Disease and injury can also erode or violate the supporting and collateral soft tissues. In the case of an insult, disruption, disease, or injury to a joint construct (spinal column [e.g., spinal facet], hip, knee, elbow, fingers, ankle, shoulder, synovium, collateral ligaments, etc.), joint capsule, ligamentous structures, or cartilaginous (collagen based) tissues, it may be necessary to manage or contain physiological biomaterial, or other therapeutic media within the joint or anatomic structure. Likewise, primary and secondary spinal tumors may contribute to a loss of tissue (bony, etc.) integrity and strength. Therefore, these tumors may serve as indications for vertebroplasty and other interventional spinal augmentation. The treatment of many other diseases of the bone and other tissues can also be facilitated by treating the diseases from within and/or proximate to the target anatomy. For example, chemotherapeutic agents could be implanted in proximity to or within a tumor. Or in the case of a failed bony fusion (pseudoarthrosis), a reoperation and revision may be avoided through the introduction of biological agents into a containment device designed to promote bony healing. In particular, bone healing by interventional means may be facilitated by the implantation of osteophilic (osteoinductive or osteoconductive) materials, which are scaffolds and/or materials used to stimulate or optimize bony healing. These materials include, but are not limited to, hydroxylapaptite (HA), tri-calcium phosphate, biocoral, bioceramics, biomaterial granules, demineralized bone matrix (DBM), bone morphogenic proteins (BMPs), and collagen. Bone morphogenic proteins (BMPs), an active ingredient in DBM and a member of the TGF-β (transforming growth factor-β) super family, mediate developmental processes that include morphogenesis, differentiation, cell survival, and apoptosis. Although the role of TGF-β is not fully understood, its net effect is an increase in bone matrix. Other factors, such as insulin-like growth factors (IGF I and IGF II) and platelet derived growth factor are also important. Unfortunately, since these proteins have short biological half-lives, they must be maintained at the treatment zone in sufficient therapeutic concentrations in order to be effective. Therefore, dilution of the therapeutic agent due to the unintentional migration of the implanted material away from the therapeutic zone is also a major challenge to good patient outcomes.
Accordingly, it would be desirable to provide treatment systems and methods that contain and deliver implanted biomaterial or other pharmacological or treatment media at any time during the treatment cycle, while preventing the unintentional migration of the implanted materials and/or controlling the release of the implanted materials into the targeted tissue or cellular treatment zone.